宇宙加速膨胀及暗物质研究

Many different observational data, such as type IA supernovae, CMB power spectrum, BAO and other data, support the conclusion that our universe is undergoing an accelerated expansion period. This discovery has stimulated many theoretical ideas and observational cosmology studies, the US , Europe and China have been developing future large projects such as LSST of the US, Euclid of ESA and Dome A telescope of China. The future obsevations will futher constrain the property of dark energy, or even reveal that dark energy may not be a constant (this is the main scientific target of Euclid for example). We are planning to numerically analyze the forthcoming data, to test many different accelerated expansion models, these will be our focus of this key project. Since the nature of dark energy depends on and builds upon the fundation of physics as well as cosmology, we will explore two directions, the first is to propose new dark nergy models, to further develop the theoretical reasoning of the holographic dark energy model and other important dark energy models, and to base these models on the fundation of entropic gravity, holography and string theory, to find possible evolution evidence of different dark energy models. The second is to theoretically and numerically study new and attractive dark energy models in detail, and to employ ideas in metamaterials to mimic cosmlogy and properties of dark energy. Last but not the least, we will study theoretical models of dark matter, to find possible relation between dark matter and dark energy.

宇宙正在加速膨胀是超新星数据、CMB数据、重子声学振荡数据以及其他一些天文观测数据支持的结论，在过去15年中已激发大量的理论和观测研究，欧美以及中国都有未来探测加速膨胀性质的重要计划，例如美国的LSST，ESA的Euclid，中国的南极Dome A望远镜，等。这些观测与实验将进一步加强对暗能量性质的限制。我们计划在用数值分析未来实验结果、检验各种加速宇宙模型方面进行重点研究。另外，暗能量的起源和本质关系到物理学以及宇宙学基础，我们将在两个方向上从事研究，一是继续从理论角度提出新的暗能量模型，推进我们已经提出的模型如全息暗能量模型的研究以及其他重要的暗能量模型的研究，在熵引力图像或弦论中找到全息暗能量以及其他可能模型的证据以及演化性质。二是在理论和数值上细致研究新的可能的模型，以及结合超颖材料模拟宇宙学手段来研究宇宙加速膨胀。最后，我们还将研究暗能量与暗物质之间可能存在的关系。

暗能量和暗物质在宇宙演化和结构形成中起到关键的作用，同时暗能量和暗物质也是基础物理面临的重大挑战。受项目资助，在暗能量和暗物质的研究方面取得以下主要成果：1）提出利用LIGO对随机引力波背景的测量来探索原初黑洞在暗物质中的丰度的方法，给出目前恒星质量原初黑洞丰度的最严格限制，并预言较小质量的原初黑洞所产生的随机引力波背景有望在不远的将来被探测到。相关结果发表在Phys.Rev.Lett（2018）。2）计算并给出任意质量谱的原初黑洞并合率公式，为将来利用统计方法重构原初黑洞的质量分布提供关键的理论基础。相关成果发表在Astrophys.J（2018）。3）在Phys.Rept.上发表一篇全息暗能量的综述文章。4）计算了预加热过程产生的随机引力波背景。